Oscillations in Closed Surge Tanks

1943 ◽  
Vol 10 (4) ◽  
pp. A183-A186
Author(s):  
A. M. Binnie
Keyword(s):  
Small Scale ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Compression And Expansion ◽  
Made In

Abstract The existing methods of predicting the oscillations in a closed surge tank are very lengthy unless drastic simplifications are made. In this paper a new and quick procedure is explained for calculating the maximum pressure and expansion of the air, which result from a sudden shutdown of the plant. Friction is taken into account, both in the pipe and also in any arrangement placed between the pipe and the tank to damp the oscillations, but the compression and expansion of the air must be assumed isothermal. Small-scale experiments confirmed the expectation that the observed maximum pressures would be greater than the theoretical. The shutdown of a big plant is, however, not instantaneous, and the theory may be expected to yield results sufficiently accurate for the purpose in view.

Influence of Surge Tank and Relief Valve on Transient Flow Behaviour in Hydropower Stations

2011 ◽  
Author(s):  
Alireza Riasi ◽  
Ahmad Nourbakhsh
Keyword(s):  
Power Plants ◽  
Transient Flow ◽  
Flow Analysis ◽  
Internal Boundary ◽  
Transient Condition ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Small Hydropower ◽  
Relief Valve ◽  
Hydropower Stations

Unsteady flow analysis in water power stations is one of the most important issues in order to predict undesirable pressure variations in waterways and also probable changes in rotor speed for the power plants safe operation. Installation of surge tank and relief valve is the two main methods for controlling of hydraulic transient. The relief valve is used in several medium and small hydropower stations instead of the surge tank and mounted on the penstock near the powerhouse. The recent generation of relief valves are reliable and beneficial and consist of fully control system that directly conducted by governor. This paper presents a numerical method for transient flow in hydropower stations using surge tank and relief valve. For this purpose the governing equations of transient flow in closed conduit are solved using the method of characteristics (MOC) using unsteady friction. Hydraulic turbine, surge tank and relief valve are considered as internal boundary conditions. The influence of surge tank and also relief valve on the maximum pressure in spiral case and turbine over speed has been studied for a real case. The results show that the transient condition is considerably improved by using a relief valve and this device can be mounted in lieu of an expensive surge tank.

The Ancient Cart-tracks of Malta

Antiquity ◽  
1954 ◽  
Vol 28 (110) ◽  
pp. 91-98 ◽  
Author(s):  
H. S. Gracie
Keyword(s):  
Agricultural Soil ◽  
Field Work ◽  
Present Writer ◽  
Small Scale ◽  
Far North ◽  
South Eastern ◽  
Close Proximity ◽  
Made In

The barren hill-tops of Malta are scored in many places by ancient ruts cut deeply into the rock. They can be seen also on the slopes and on the lower plains, but less frequently because these areas are normally under agricultural soil. They always occur in pairs from 52 to 58 inches apart and were quite clearly used by vehicles. They have been discussed in print for 300 years but no agreement has been reached on how, when or why they were made or what vehicles used them. In fact, there are as many theories as there are authors. Of these writers only Captain E. G. Fenton and Professor Sir T. Zammit appear to have done any serious field work, and none has published a map. The present writer, therefore, decided to attempt the laborious task of plotting them, making such other observations and measurements as he could. Zammit, in the paper cited, reproduced some excellent photographs from both the ground and the air, to which the reader is referred.Time did not permit an examination of the whole island and few observations were made in the low-lying south-eastern part. A fairly intensive survey was made of the high ground as far north as the Baida Ridge, which joins the northern shores of Ghain Tuffieha Bay and St. Paul’s Bay. Two portions of the map are reproduced here. Where there are a number of parallel tracks in close proximity they are shown on the map as one on account of the necessarily small scale used. The gaps in the routes are mainly due to cultivated patches, and no attempt has been made to bridge them by conjecture.

scholarly journals Pengembangan Rubrik Penskoran pada Asesmen Otentik untuk Materi Volume dan Luas Balok

2020 ◽  
Vol 4 (2) ◽  
pp. 275
Author(s):  
Yunita Rochmawati Jonan
Keyword(s):  
Authentic Assessment ◽  
Student Response ◽  
Small Scale ◽  
Development Research ◽  
Test Results ◽  
Assessment Of Learning ◽  
Teachers And Students ◽  
Scoring Rubric ◽  
Large Groups ◽  
Made In

ABSTRAK Tujuan penelitian pengembangan ini adalah menghasilkan sebuah rubrik penskoran pada asesmen otentikuntuk materi volume dan luas balok yang dapat digunakan oleh guru dan siswa. Rubrik ini dibuat sesuai dengan standar penilaian dalam kurikulum 2013. Penelitian pengembangan (R&D) ini menggunakan model Borg and Gall yang terdiri dari lima tahap yaitu penelitian dan pengumpulan data awal, perencanaan, pengembangan format produk, uji coba skala kecil, revisi akhir dan penyempurnaan produk. Hasil penelitian pengembangan ini berupa rubrik penyekoran holistik dan analitik dengan nilai sangat valid sebesar 94%. Analisis dari penelitian ini adalah angket kebutuhan bagi guru dan siswa sedangkan uji coba dilakukan melalui perorangan, kelompok kecil dan kelompok besar. Sedangkan kelayakan rubrik penskoran dari penilaian oleh ahli dengan menggunakan angket uji validitas materi, hasil belajar siswa, respon siswa serta tanggapan guru pengajar. Hasil penelitian ini menunjukkan bahwa rubrik penskoran ini efektif dalam membantu memperbaiki hasil ulangan dan cukup praktis serta dapat dipergunakan untuk memberikan penilaian hasil belajar yang sesuai dengan kurikulum 2013. Kata kunci: rubrik, penskoran, asesmen otentik.   ABSTRACT The purpose of this development research is to produce a scoring rubric on an authenticity assessment for the volume and area materials that can be used by teachers and students. The rubric is made in based on the assessment standards in the 2013 curriculum. This development research (R&D) uses the Borg and Gall model consisting of five stages of preliminary data research and collection, planning, product format development, small-scale trials, final revisions and product enhancements. The results of this development research include holistic and analytic scoring rubric with a very valid score of 94%. The rubric is analyzed fromquestionnaire for teachers and students, while trials are conducted through individuals, small groups and large groups. The feasibility of the scoring rubric from assessment by members by using the material validity test questionnaire, student learning results, student response and teacher responses. The results of this study show that the scoring rubric is effective in helping to improve the test results and is practical and can be used to provide assessment of learning outcomes in accordance with the 2013 curriculum. Keywords: rubric, scoring, authentic assessment.

scholarly journals XX. On the alloys of steel

1822 ◽  
Vol 112 ◽  
pp. 253-270 ◽  
Keyword(s):  
Considerable Degree ◽  
Small Scale ◽  
Royal Institution ◽  
Extended Scale ◽  
Made In ◽  
At Home

The alloys of steel made on a small scale in the laboratory of the Royal Institution proving to be good, and the experiments having excited a very considerable degree of interest both at home and abroad, gave encouragement to attempt the work on a more extended scale, and we have now the pleasure of stating, that alloys similar to those made in the Royal Institution, have been made for the purpose of manufacture; and that they prove to be, in point of excellence, in every respect equal, if not superior, to the smaller productions of the laboratory

Servovalve-Controlled Pneumatic Suspensions

1979 ◽  
Vol 21 (1) ◽  
pp. 7-18 ◽  
Author(s):  
E. Esmailzadeh
Keyword(s):  
Relative Displacement ◽  
Suspension System ◽  
The Body ◽  
Analogue Computer ◽  
Surge Tank ◽  
Low Frequencies ◽  
Ground Vehicle ◽  
Pneumatic Suspension ◽  
Vehicle Suspension System ◽  
Made In

A linear analytical model of a ground-vehicle suspension system employing a pneumatic isolator and a three-way servovalve is developed. Damping is provided by connecting the pneumatic spring to a constant-volume surge tank through capillary resistances. Non-dimensional dynamic equations for the valve-controlled, self-damped, pneumatic isolator are derived and the effects of various feedback and feedforward controls on the performance of the closed-loop system are pointed out. Experiments are conducted to verify the validity of the assumptions made in deriving the absolute and relative displacement transmissibilities and the vehicle model is simulated on an analogue computer. It is shown that a servovalve-controlled pneumatic suspension system not only considerably reduces the body transmissibility at very low frequencies, but is also capable of very good isolation throughout the broad frequency range.

Tracing Small-Scale Fluctuations in the Soft X-ray Background

1997 ◽  
Vol 166 ◽  
pp. 321-324
Author(s):  
R. Warwick ◽  
I. Hutchinson ◽  
R. Willingale ◽  
K. Kuntz ◽  
S. Snowden
Keyword(s):  
Column Density ◽  
Galactic Halo ◽  
Inverse Correlation ◽  
Line Of Sight ◽  
Small Scale ◽  
X Ray ◽  
Hydrogen Column Density ◽  
X Ray Background ◽  
Counting Statistics ◽  
Made In

AbstractAn overlapping set of ROSAT PSPC observations made in a region of very low Galactic foreground column density, has been used to investigate variations in the soft X-ray background on angular scales of 15′ – 5°. In the ¼ keV band there is a clear inverse correlation of the count-rate with the line-of-sight hydrogen column density. However, after correcting for this absorption effect, strong residual fluctuations remain in the data, with an amplitude which is significantly larger than that due to the counting statistics or the confusion of unresolved discrete sources. In contrast a similar analysis for the ¾ and 1.5 keV ROSAT bands shows no evidence for an excess signal. The most likely origin of the ¼ keV fluctuations would seem to be in a patchy distribution of ~ 106 K gas in the Galactic halo.

scholarly journals Ice Nuclei in the Ultramicroscope and the Atmosphere

1949 ◽  
Vol 1 (6) ◽  
pp. 310-314
Author(s):  
E. M. Fournier d’Albe
Keyword(s):  
Present Article ◽  
Ice Crystals ◽  
Small Scale ◽  
Ice Nuclei ◽  
Laboratory Results ◽  
Made In ◽  
Stimulation Of

AbstractVarious attempts have been made in recent years to overcome the difficulties inherent in the study of clouds by reproducing them on a small scale in the laboratory. The present article briefly reviews some of these experiments, particularly those relating to the formation of ice crystals, and discusses the extent to which the laboratory results accord with what is known of natural clouds. Recent experiments on the artificial stimulation of rainfall are also examined for the light they throw on the part played by ice nuclei in the formation of rain.

scholarly journals Advances in understanding and parameterization of small-scale physical processes in the marine Arctic climate system: a review

2014 ◽  
Vol 14 (17) ◽  
pp. 9403-9450 ◽  
Author(s):  
T. Vihma ◽  
R. Pirazzini ◽  
I. Fer ◽  
I. A. Renfrew ◽  
J. Sedlar ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Sea Ice ◽  
Surface Fluxes ◽  
Climate System ◽  
Arctic Climate ◽  
The Arctic ◽  
Small Scale ◽  
Climate Modelling ◽  
Physical Processes ◽  
Made In

Abstract. The Arctic climate system includes numerous highly interactive small-scale physical processes in the atmosphere, sea ice, and ocean. During and since the International Polar Year 2007–2009, significant advances have been made in understanding these processes. Here, these recent advances are reviewed, synthesized, and discussed. In atmospheric physics, the primary advances have been in cloud physics, radiative transfer, mesoscale cyclones, coastal, and fjordic processes as well as in boundary layer processes and surface fluxes. In sea ice and its snow cover, advances have been made in understanding of the surface albedo and its relationships with snow properties, the internal structure of sea ice, the heat and salt transfer in ice, the formation of superimposed ice and snow ice, and the small-scale dynamics of sea ice. For the ocean, significant advances have been related to exchange processes at the ice–ocean interface, diapycnal mixing, double-diffusive convection, tidal currents and diurnal resonance. Despite this recent progress, some of these small-scale physical processes are still not sufficiently understood: these include wave–turbulence interactions in the atmosphere and ocean, the exchange of heat and salt at the ice–ocean interface, and the mechanical weakening of sea ice. Many other processes are reasonably well understood as stand-alone processes but the challenge is to understand their interactions with and impacts and feedbacks on other processes. Uncertainty in the parameterization of small-scale processes continues to be among the greatest challenges facing climate modelling, particularly in high latitudes. Further improvements in parameterization require new year-round field campaigns on the Arctic sea ice, closely combined with satellite remote sensing studies and numerical model experiments.

Druckmessungen mit piezoelektrischen Sonden an einem linearen Z-Pinch

1964 ◽  
Vol 19 (6) ◽  
pp. 690-696 ◽  
Author(s):  
Klaus Büchl
Keyword(s):  
Momentum Flux ◽  
High Sensitivity ◽  
Good Time ◽  
Pressure Sensitive ◽  
Compression And Expansion ◽  
Kinetic Pressure ◽  
Z Pinch ◽  
Piezoelectric Probes ◽  
Probe Measurements ◽  
Made In

The radial distribution of the dynamic and kinetic pressure in a linear Z-pinch-discharge has been investigated with piezoelectric probes. The electrical signals from the probe are proportional to the momentum flux on the pressure-sensitive surface. The momentum flux is anisotropic, because there are radial plasma streams during the compression and expansion of the plasma cylinder. The dynamic and kinetic pressure were determined from the momentum flux by comparing the probe measurements made in different directions. The conditions and construction of the probe necessary for both a good time resolution and high sensitivity are described. The probes have time resolutions and sensitivities of 0.6 μs and 7.7 Torr/mV and 0.8 μs and 2.0 Torr/mV respectively.

Spray Wall-Impingement from a Single Hole Nozzle under Common Rail Condition

2011 ◽  
Vol 347-353 ◽  
pp. 770-773 ◽  
Author(s):  
Zhan Cheng Wang ◽  
Hui Yong Du ◽  
Jian Xin Liu ◽  
Liang Han ◽  
Song Liu
Keyword(s):  
Combustion Process ◽  
Common Rail ◽  
Small Scale ◽  
Rail Pressure ◽  
Mixture Formation ◽  
Common Rail Pressure ◽  
Wall Impingement ◽  
Inclination Angles ◽  
Spray Impingement ◽  
Made In

In the middle and small scale diesel engine, the interaction between the spray wall-impingement and air motion plays a fundamental role on the mixture formation process, it also greatly influences the combustion process and the exhaust emissions. An experimental setup for spray impingement visualization has been made in this paper, the influences of common rail pressure and variable inclination angles on spray impingement are investigated. The experimental results show that the splashing volume increases according to the increasing common rail pressure, and the better atomization is achieved. As for variable inclination angle of spray, the upstream of impingement spray decreases and the downstream increases with the increase of inclination of the wall, the change of entrainment is hardly detected, but the overall splashing volume increases slightly.

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